Engine or pump having rotors defining chambers of variable volumes



Jan. 4, 1966 Filed Feb. 9, 1965 L.BARTOLOZZI ENGINE OR PUMP HAVING ROTORS DEFINING CHAMBERS OF VARIABLE VOLUMES 4 Sheets-Sheet 1 Jan. 4, 1966 BARTOLOZZI 3,227,090

ENGINE OR PUMP HAVING ROTORS DEFINING CHAMBERS OF VARIABLE VOLUMES Filed Feb. 9, 1965 4 Sheets-Sheet 2 Jan. 4, 1966 L. BARTOLOZZI PUMP HAVING ROTORS ERS OF VARIABLE VOL DEFINING UMES ENGINE OR GHAMB 4 Sheets-Sheet 3 Filed Feb. 9, 1965 Jan. 4, 1966 BARTOLCZZI ENGINE OR PU MP HAVING ROTORS DEFINING CHAMBERS OF VARIABLE VOLUMES 4 Sheets-Sheet 4 Filed Feb. 9, 1965 Fig.12

United States Patent 0 3,227,090 ENGINE OR PUMP HAVING ROTORS DEFINING CHAERS 0F VARIABLE VOLUMES Luigi Bartolozzi, Via Gaetano Milanesi 14, Florence, Italy Filed Feb. 9, I965, Ser. No. 431,406 Claims priority, application Italy, Dec. 2, I969,

20,948/60, Patent 637,255 7 Claims. (Cl. I03I29) This application is a continuation-in-part of my copending application, Ser. No. 154,758, filed Nov. 24, 1961, now abandoned.

The invention relates to a machine or mechanism operable with compressed gas or a fluid as a motor or as a pump. The invention is applicable also to use in an internal combustion engine.

The machine includes a casing in which is an annulan shaped chamber. In the casing is an axial shaft. On the shaft are rotors in the form of rings with radial pistons. The rings are rotated in only one and same direction. The rings rotate around the same axis and are alternately moved in such a manner that while one ring is rotating, the other one is fixed and vice-versa. Concentric with and inside the annular chamber is a distributor whose motion is in a direction contraiy to that of the rings and pistons. This motion is relatively very slow and takes place by short steps or trips by etlect of a stress which may also be due to the fluid current passing through the distributor.

In one practical embodiment there are provided two 4 adjacent and coaxial rings, which define inner walls of the annular chamber. Outer and lateral walls are defined by a cylindrical casing. Each of the rings has a pair of diametrally opposed radial pistons which extend for the entire radial section of the annular chamber. The pistons borne by one of the rings extend over the other ring as a seal, besides forming a seal with the outer end and lateral walls of the casing.

In the interior of the rings there is provided a distributor rotor, which moves at controlled steps in a direction opposite to the direction of motion of the rings to determine the succession of cycles in the machine. The distributor rotor is provided with fluid or gas supply ports and discharge ports. In an internal combustion engine, the distributor rotor also has ignition means and means for determining instants of increase of pressure and temperature of the fluid in the combustion chamber during the ignition stage.

The two rings with the associated radial pistons are provided with mechanical means to permit movements in only one direction to each of the two rings. Further mechanical means stop the rings after having accomplished an angular stroke equal to 360/n, where n is the number of the radial pistons of each of the rings, minus a small angular amount.

The invention will be better understood from the following description and the accompanying drawings, which illustrate embodiments of the invention.

Referring to the drawings:

FIGURE 1 is a cross-section of a steam, gas or fluid driven engine embodying the invention.

FIGURE 2 is a section taken along the broken line II-II of FIG. 1.

FIGURE 3 is a perspective View of two rings with associated pistons.

FIGURES 4, 5, 6 and 7 are sectional views similar to FIG. 1 showing the operation cycle of the machine.

FIGURE 8 is a sectional view taken along the line VIII-VIII of FIG. 2 showing structure allowing rotational motion of the rings in only one direction.

FIGURES 9 and 10 are sectional views of a structure for stopping rotation of the rings and controlling rotaice tion of the distributor internal with respect to the rings.

FIGURE 11 is a local section taken along the broken line XI-XI of FIG. 9.

FIGURE 12 is a sectional view partially diagrammatic of another embodiment of the invention.

FIGURES l3 and 14 are transverse and longitudinal sections similar to FIGS. 1 and 2 respectively, of an internal combustion engine embodying the .invention.

In FIGS. 1 to 7 an outer cylindrical casing I is provided with end walls 2. Coaxially with and inside the casing are two annular rings 3, 4. The rings are located side by side and cooperate with the end walls 2 and the outer wall I to define an annular chamber. The rings 3, 4 respectively carry diametrally opposite radial pistons 5, s and 7, 8 which are extended radially of the entire section of the annular chamber; these radial pistons are internally hollow. Each piston extends axially beyond one of the rings abutting on another ring located alongside and coaxial. The pistons form seals between the rings and outer casing wall. Adjacent each of the radial pistons there are provided ports 9, I0 and 11, 12 respectively.

A drive shaft 15 is mounted by means of bearings 15a on end flanges I4, which are secured to the casing formed by the members I, 2, 2. These flanges have fluid or gas supply passage 16 and discharge conduit 17, respectively. On the drive shaft 15 which is coaxial with rings 3, 4 and walls 1, 2 there is assembled rotatively integral a pair of cylindrical members l8, 19 provided with cup flanges having openings 18a, 19a and designed to define a fluid supply and respectively discharge manifold. Between the flanges of two members 18, 19 there is a freely rotatable cylindrical distributor rotor 21 which is conentric with and internal to rings 3, 4 and located to seal with the internal surfaces of rings 3 and 4 and to cooperate with the ports 9 to 12. The rotor has radial extensions which define with the rings 3 and 4, a pair of supply or discharge chambers 23 which are extended circumferentially rather widely. The radial walls of the distributor rotor 21 also define two narrow discharge or supply chambers 24. The two wide chambers 23 communicate with the manifold of the member 18 and thus with the supply passage 16. The chambers 24, through the manifold formed by the member l9, communicate with the discharge conduit 17. In chambers 23 the rotor 21 forms fins 21a, which owing to the entering fluid current tend to rotate the rotor 21 in a direction contrary to that of the rings 3 and 4.

The rings 3 and 4 are capable of rotating in only one direction and they rotate alternately and transmit the movement (operating as motor) to the shaft IS. The distributor rotor 21 is capable of rotating only in the opposite direction. In order to effect the rotation in only one direction of rings 3, 4 there may be provided between the stationary end walls 2 and end flanges 14 on one side and rings 3, respectively 4 on the other side a mechanism as indicated in FIG. 8 to which reference is now made and concerning the mechanism relative to the ring 3. In FIG. 8 and also in FIG. 2, ring 3 is shown integral with an annular projection 3a, which is provided with inner and outer circumferentially extending tapered or wedge-like slots SI and S2. A similar projection 40 (see FIG. 2) is provided integral with the ring 4. Coupling rollers RI and R2 are freely disposed for rolling in the slots. The narrowest width of the slots is less than the diameters of the rollers. The annular projection 3a is radially interposed between the member 18, which is secured to shaft 15, and a step formed by the corresponding end wall 2, which is stationary; similarly the projection 4a is radially interposed between the member 19, secured to the shaft 15 and the other stationary wall 2. The distributor rotor 21 is free- 1y rotatable around the shaft in the space between the members 18 and 19. When ring 3 is urged by fluid pressure to rotate in a clockwise direction as viewed in FIG. 8, rollers R2 engage member 18 so that the ring 3 is in effect coupled to the shaft 15. Ring 4 is provided with a similar annular projection 4a with slots as shown in FIG. 2 and the rollers would in a similar manner be coupled to the shaft 15 via member 19. The shaft 15 is free to rotate in a clockwise direction with respect to the rings 3 and 4 even when these rings are stationary since the rollers R2 roll away from the narrower parts of the slots S2.

When one of the rings 3 or 4 is urged by the fluid pressure to move in a counterclockwise direction as viewed for the ring 3 with relative annular projection 3a in FIG. 2, the rollers R1 engage in the narrower parts of slots S1 at the stationary casing members 2, 14, thus preventing counterclockwise rotation of the rings with respect to the casing. Thus, the rotors shown in FIGS. 1-7 formed respectively by ring 3 with pistons 5, 6 and by ring 4 with pistons '7, 8 are independently prevented from rotation in a direction (the counterclockwise direction considering FIG. 8) and each can rotate in clockwise direction operating the shaft 15. The showing of slots S1, 52 has been omitted from FIG. 3 to simplify the drawing.

FIGS. 9, 10 and 11 show in detail the structure or mechanism for stopping the motion of the rotor of the distributor 21 each time after a ring 3 or 4 has moved slightly less than 180 the distributor rotor 21 rotating a few degrees.

The distributor 21 in its central part is provided with two tapered inclined profiles 34 terminating with two teeth 34a. The members which have to lock the teeth 34a are two pawls 31 and 32, hinged in the rings 4 and 3 respectively. The pawl 31 of the ring 4 (see in particular FIG. 10) is made of a link rod 31b hinged in 31a! to the ring 4 and hearing at the end a roller 31c and an articulated bracket 31d. The pawl 32 is similar to that 31. In the rings 3 and 4 there are provided inclined profiles and 35a, tapered too as those 34 and facing these latter; said inclined profiles 35 and 35a of each ring are made up along the internal edge of the ring adjaccntly the other ring. The bracket (as that 31d) of each pawl borne by one of the rings acts in contact with the internal surface of the other ring and with the bottom surface of the inclined profile of the other ring; to this purpose the bracket is shaped with a curved surface substantially corresponding to those on which it slides. When the bracket of the pawl of a ring is in correspondence with the concentric portion of the other ring internal surface, it prevents the pawl from rotation outwardly and this pawl retains the distributor 21 resting and pressing against the pawl with one of the shoulders 34a; in FIG. 9 the pawl 31 on the contrary is retaining the distributor and is stressed to rotate in clockwise direction until it lies down, being precluded therefrom by its own bracket contrasting with the internal profile of the ring 3. When one of the rings begins its stroke, it operates its pawl, which previously had retained the tooth 34:11; in FIG. 9 the ring 3 with the pistons 5 and 6 operates the pawl 32, which is lying down, i.e. in tangential position. This pawl 32 slides with its bracket on the inclined bottom 35a of the stationary ring thus beginning to set upright from the lying down position towards the radial one end inwardly. At the end of the stroke of about 180 of the ring 3, the pawl 32 has set upright and is located radially inwardly adjacently the pawl 31, while the pawl 31 is inclined, i.e. completely lying down in the housing 35 made up in the ring 4, releasing the distributor tooth 34a. The distributor then, owing to the fluid stressing on the fins 21a, rotates until approaching with the tooth 31a the pawl 32 (which now is not more allowed to move from the radial retaining position). By moving the distributor 21 the feed is changed over and it is now the ring 3 which is stressed to rotate in an opposite direc tion and thus sticks on the casing 2, 14, as explained above;

on the contrary, the ring 4 is now thrusted by the fluid and begins now to rotate operating the pawl 31 lying down; the cycle goes on as described. Thus the stops of the distributor 21 are controlled only by the rings 3 and 4 by means of the angular movements of the pawls retaining the rotor while the distributor is only stressed to rotate in a direction opposite to that of the motor. Of course the pistons are moved by the gases which, at the beginning of the stroke, find the supply ports always open.

The operating cycle of the engine is illustrated in FIGS. 1 and 4 to 7 where it is assumed that the rotation of the pistons 5-8 is clockwise and the rotation of the distributor rotor 21 is counterclockwise. Starting from the position of FIG. 1, a supply of fluid under pressure passes from the passage 16 through the openings 18a, the chamhers 23 and the ports 10 and 9 to the cavities A and C, defined between pistons 6, 8 and 5, 7 respectively. Simultaneously the cavities B and D between pistons 5, 8 and 6, '7 are put in communication through the ports 11 and 12 with the discharge chambers 24 and thus through the openings 19a with the discharge passage 17. Under these conditons, the supply of the pressurized fluid from the passage 16 continues until the ports 10 and 9 are supplied or fed by the chambers 23, until the ports 9 and 11) remain uncovered and then until the fluid is expanded. The chambers A and C thus increase in their volume while the chambers B and D discharge through the ports 11 and 12 (see FIG. 4). When the ring 3 and pistons 5, 6 have moved from the position of FIG. 1 to that of FIG. 5, ring 3 stops in a position wherein the volumes of the chambers B and D are minimized. In the meanwhile the distributor 21 rotates from the position of FIG. 5 to the position of FIG. 6, whereby the fiuid supply is now fed to the chambers B and D and the discharge takes place from the chambers A and C as in FIG. 6, while ring 3 is standstill and ring 4 moves. FEG. 7 illustrates a subsequent position arrangement of the engine members.

Thus, a reciprocal movement and stopping of each of the rotary rings 3, 4 occurs. The radial pistons of each ring cyclically follow the pistons of the other ring. Thus, in each moment, the pistons of one rotary ring are sta tionary while the other ones are in motion and vice-versa. The distributor rotor 21 is stressed in the counterclockwise direction by an external drive means or by the supply fluid through the fins 21a integral with the distributor rotor 21, which fins impart a force to the distributor rotor 21.

Alternatively, the distributor 21 may be stressed by an external means, such as a tubular shaft around the shaft 15.

In FIG. 12, the cylindrical casing 41 is similar to casing 1, 2 of FIGS. 1 and 2. Casing 41 operates likewise on the stationary shaft 42. The motions of the parts are reversed from those previously described. The casing 41 moves with respect to the shaft; means similar to those S1, R1 transmit the motion to the casing 41, while means similar to those S2, R2 prevent the rings 3 and 4 from rotation in a direction opposite to that of the casing 41. The feed and discharge take place, in this case, through the stationary shaft.

In the embodiment of FIGS. 13 and 14, which show an internal combustion engine, the system is substantially equivalent to that of FIGS. 110. The members which form the chambers of variable volume are substantially equivalent; 1fi1, 162, 1193, 1114, 105, 1%, 167, 198 denote members equivalent to those 1 to 8. The dis tribution system is modified in that a distributor rotor 121 is located inside the rings 10? and 104 and forms a supply chamber 121a. This chamber extends circumferentially through an angle substantially equal to the stroke of each radial piston. There is also provided a discharge chamber 12111 with a discharge opening 1210 and a combustion chamber 121d. Chamber 121d has a very narrow angular extension. Chamber 121d extends from the periphery of the distributor 121 to a central cavity therein through which a shaft 122 extends. In shaft 122 there is provided a central cavity communicating with the chamber 1210! through radial slots 124 distributed circumferentially in the shaft 122; in said cavity ignition plugs 123 project, axially arranged on the shaft 122. A linkage 125 or other suitable means allows control of the ignition system, starting from a cam profile of the rotating members 3 and 4.

In this internal combustion engine, during the cycle starting from the arrangement of FIG. 13 in the chamber A, the fuel supply is received through the slot 116 corresponding to the slot of ring 3 in FIG. 3. The discharge from the chamber B is determined through the opening 111 corresponding to that of slot ll in ring 4. In chamber C the ignition takes place through the chamber 121d and the opening 109 corresponding to slot 9 of ring 3. The ignition is determined by the spark plugs 123 which can easily be removed for cleaning and replacement. From the chamber D the discharge stage develops through the opening 112 in the discharge chamber 12112. Opening 112 corresponds to slot 12 of ring 4. Departing from the arrangement of FIG. 13, the pair of pistons 5 and a move in the direction of the arrows as indicated owing to the expansion of the chamber. The increase of volume of the chamber C is determined by the combustion and thus the expansion and the increase of volume of chamber C itself. This increase causes the gas intake into chamber A. The chambers B and D are then reduced in volume. In the chamber B there is determined compression of the gas, the opening 111 being closed. The chamber D effects discharge through the openings 112 and 1210. After the stopping of the rotor 103. 165, 106 with the piston 1&5 adjacent to piston 1% and the piston 11% adjacent to piston 167 due to counterclockwise motion of the distributor rotor 121, the cycle reverses and an explosion occurs in chamber B as the chamber 121d is moved at opening 111 while the other chambers accomplish subsequent cycles like those previously described. The motion is drawn by the gear 122a of shaft 122.

Thus, as already stated, for FIG. 11, by reversing the operation of the device of FIG. 2, from movable to stationary, the shaft is fixed and the casing rotates so that the device assumes the form of a motor-flywheel-pulley.

While I have shown and described what I believe to be the best embodiments of my invention, it will be apparent to those skilled in the art that various changes and modifications may be made therein without departing from the spirit and scope of the invention as defined 1n the appended claims.

What I claim is:

l. A pressurized fluid engine, comprising in combinaon: U (a) a stationary closed generally cylindrical casing;

(b) a rotatable shaft passing axially through the cas- (c) two cylindrical members integral with and ax ally spaced on the shaft, said members having openings therein;

(d) means defining fluid supply and discharge ports at opposite ends of the casing and communicating with the openings in the respective members;

(e) a distributor rotor with diametrally ahgned apertured axial extensions freely rotatable on said shart inside the casing; l

(f) two rotary units each including a ring and two diametrally aligned radial pistons; said units being rotatably mounted on said distributor rotor with the rings in axial alignment; said axial extensions defining with the rings and distributor rotor two angularly wider fluid feeding chambers and two angularly narrower fluid discharge chambers;

(g) means located between said rings and said casing for limiting both of said rings to rotation in only one direction and for precluding rotation of said rings in the opposite direction;

(h) means for coupling the rings to the shaft for rotating the shaft upon sequential angular movements of the rings and for allowing rotation of the shaft; said distributor rotor having inclined. passages operating as vanes actuated by said fluid to cause rotation of the rotor in a direction opposite to that of the rings; and

(j) pairs of pawls carried by the rings and having rollers thereon; said distributor rotor and rings having inclined surfaces engaged by the rollers to limit rotation of the rings after each ring has moved through an angle slightly less than said pistons defining with said rings and casing four other chambers having variable volumes as each ring rotates in turn with respect to the other; said rings having openings near the pistons providing communication between said other chambers and the first named fluid feeding and fluid discharge chambers; whereby the shaft is rotated in said one direction as said other chambers alternately fill with and discharge fluid while the rings alternately and sequentially rotate in said one direction.

2. An engine according to claim 1, wherein the means for limiting each of the rings to rotation in one direction comprises on the ring slots having tapered sides facing the casing, and rollers disposed in the slots for engaging said each ring to the casing, at narrower portions of the slots.

3. An engine according to claim 1, wherein the means for coupling each of the rings to the shaft comprises on the ring slots having tapered sides facing said cylindrical members and rollers in said slots for engaging between said rings and members at narrower portions of the slots.

4-. In an engine, in combination:

(a) a stationary closed general cylindrical casing;

(b) a rotatable shaft passing axially through the cas- (c) members integral with the shaft and having openings therein;

(d) means defining fluid supply and discharge ports for the casing; said ports communicating with the opening in said members; i

(e) a distributor rotor freely rotatable on said shaft in the casing;

(f) two axially aligned rings mounted on said dis tributor in the casing to define an annular cavity with the casing;

(g) said rotor having radial extensions defining fluid feed chambers and fluid discharge chambers with said rings;

(h) unidirection coupling means cooperating between the casing and each of said rings to allow rotation in a single direction of each of said rings in turn;

(i) unidirectional coupling means cooperating between the rings and said members to couple said shaft in rotating during angular movements of the rings;

(j) means associated with the distributor rotor to rotate the distributor rotor slowly in a direction opposite the shaft;

(k) means on each of the rings to determine interniittent rotation of the distributor rotor through small angles while the rings alternately rotate through angles of slightly less than 180;

(1) radially extending pistons on each of the rings extending to the casing and above the other ring and defining with the rings and casing four other chambers having variable volumes as the rings rotate with respect to each other; said rings having passages therein located rearwardly of the pistons in the direction of rotation of the rings; said passages communicating between said other chambers and said fluid feed and discharge chambers; whereby said shaft rotates in said single direction as the rings alternately rotate.

5. In an engine, in combination:

(a) means rotatably supporting a generally cylindrical casing;

(b) a stationary shaft passing axially through the cas- (c) members integral with the shaft and having openings therein;

(d) means defining fluid supply and discharge ports for the casing; said ports communicating with the opening in said members;

(e) a distributor rotor freely rotatable on said shaft in the casing;

(f) two axially aligned rings mounted on said distributor in the casing to define an annular cavity with the casing;

(g) said rotor having radial extensions defining fluid feed chambers and fluid discharge chambers with said rings;

(h) unidirectional coupling means cooperating between the ring and said members to allow rotation of the rings in a single direction of each of the rings in turn;

(i) unidirection coupling means cooperating between the casing and each of said rings to connect said casing rotating during the angular displacement of the rings;

(j) means associated with the distributor rotor to rotate the rotor slowly in a direction opposite to that of the rings;

(k) radially extending pistons on each of the rings extending to the casing and above the other ring and defining with the rings and casing four other chambers having variable volumes as the rings rotate with respect to each other; said rings having passages therein located rearwardly of the pistons in the direction of rotation of the rings; said passages communicating between said other chambers and said fluid feed and discharge chambers; whereby said casing rotates in a single direction as the rings rotate alternately with respect to the stationary shaft.

6. A pump, comprising in combination:

(a) a stationary casing;

(b) a rotatable drive shaft extending axially through the casing;

(c) members integral with said shaft having fluid feed and discharge openings;

(d) means defining inlet and outlet ports for the casing communicating with said feed and discharge openings respectively;

(e) a distributor rotor freely rotatable on said shaft in the casing;

(f) two axially aligned rings rotatably mounted on said rotor in the casing and defining an annular cavity with the casing;

(g) said rotor having axial extensions defining fluid intake and discharge chambers;

(h) unidirectional coupling means cooperating with the stationary casing and each of the rings to allow rotation of the rings in a single direction;

(i) unidirectional coupling means cooperating between the rings and said members to couple the rings and shaft in rotation and to impose alternate rotational movement on the rings;

(j) means for rotating said distributor rotor slowly and intermittently in a direction opposite to the shaft;

(k) means on the rings to determine intermittent rotation of the distributor through small angles and to determine intermittent rotation of the rings for angles slightly less than (1) pistons on each of said rings extending radially to the casing and defining four other chambers having variable volumes; said rings having passages communicating between the chambers of variable volume and the intake and discharge chambers for feeding fluid towards and from the chambers of variable volume, whereby fluid enters said inlet port and leaves said discharge port while the shaft is rotated and the rings alternately rotate in said single direction while said other chambers alternately expand and contract as fluid enters and leaves the same.

7. An engine, comprising in combination:

(a) a stationary closed generally cylindrical casing;

(b) a rotatable shaft passing axially through the casing; said shaft having an ignition chamber formed therein with a plurality of circumferentially dis tributed slots;

(c) ignition means axially mounted on said shaft and operable in said ignition chamber;

(d) two members integral with the shaft and having openings therein;

(e) means defining fluid supply and discharge ports for the casing communicating with the openings in said members;

(f) a distributor rotor freely rotatable on said shaft at the ignition cavity and between said members; (g) two axially aligned rings mounted on said rotor; (11) means on the rotor defining between said rings a wider fluid feed chamber, a narrower combustion chamber communicating with the ignition chamber,

and a fluid discharge chamber;

(i) means cooperating between the casing and each of the rings to allow rotation of the rings in a single direction;

(j) means cooperating between the rings and said members to couple the rings to the shaft for turning the shaft during angular movements of the rings;

(1:) means in the distributor rotor for causing the rotor to be slowly rotated in a direction opposite to the drive shaft by flowing fluid;

(1) means between the rings and rotor to limit rotation of the rings to slightly less than 180 and to limit rotation of the rotor to small angles;

(n1) two pistons extending radially from each of the rings to the casing and defining four chambers having variable volumes as the rings turn with respect to each other in sequence; said rings having passages communicating between the four chambers and the fluid feed, combustion and discharge chambers; whereby feed, compression, expansion and discharge of the fluid takes place in the chambers of variable volumes during alternate motion of the rings and pistons carried thereon.

References Cited by the Examiner UNITED STATES PATENTS 886,279 4/1908 Vervoort 123-11 2,149,143 2/1939 Landenberger 103-129 2,367,676 1/1945 Griffith 123-11 2,413,734 1/1947 Schroeder 123-11 2,426,361 8/1947 Lester 103-129 2,620,778 12/1952 Duckworth 123-11 2,756,728 7/1956 Mallinckrodt 123-11 2,810,371 10/ 1957 Bancroft 123-11 2,816,527 12/1957 Palazzo 123-11 2,852,007 9/1958 Bancroft 123-11 DONLEY J. STOCKING, Primary Examiner. 

1. A PRESSURIZED FLUID ENGINE, COMPRISING IN COMBINATION: (A) A STATIONARY CLOSED GENERALLY CYLINDRICAL CASING; (B) A ROTATABLE SHAFT PASSING AXIALLY THROUGH THE CASING; (C) TWO CYLINDRICAL MEMBERS INTEGRAL WITH AND AXIALLY SPACED ON THE SHAFT, SAID MEMBERS HAVING OPENINGS THEREIN; (D) MEANS DEFINING FLUID SUPPLY AND DISCHARGE PORTS AT OPPOSITE ENDS OF THE CASING AND COMMUNICATING WITH THE OPENINGS IN THE RESPECTIVE MEMBERS; (E) A DISTRIBUTOR ROTOR WITH DIAMETRALLY ALIGNED APERTURED AXIAL EXTENSIONS FREELY ROTATABLE ON SAID SHAFT INSIDE THE CASING; (F) TWO ROTORY UNITS EACH INCLUDING A RING AND TWO DIAMETRALLY ALIGNED RADIAL PISTONS; SAID UNITS BEING ROTATABLY MOUNTED ON SAID DISTRIBUTOR ROTOR WITH THE RINGS IN AXIAL ALIGNMENT; SAID AXIAL EXTENSIONS DEFINING WITH THE RINGS AND DISTRIBUTOR ROTOR TWO ANGULARLY WIDER FLUID FEEDING CHAMBERS AND TWO ANGULARLY NARROWER FLUID DISCHARGE CHAMBERS; (G) MEANS LOCATED BETWEEN SAID RINGS AND SAID CASING FOR LIMITING BOTH OF SAID RINGS TO ROTATION IN ONLY ONE DIRECTION AND FOR PRECLUDING ROTATION OF SAID RINGS IN THE OPPOSITE DIRECTION; (H) MEANS FOR COUPLING THE RINGS TO THE SHAFT FOR ROTATING THE SHAFT UPON SEQUENTIAL ANGULAR MOVEMENTS OF THE RINGS AND FOR ALLOWING ROTATION OF THE SHAFT; SAID DISTRIBUTOR ROTOR HAVING INCLINED PASSAGES OP- 